CONVERSION BASE 10 => BASE N ET INVERSEMENT

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class Conversions {

	//declarations des composants graphiques
	
	private JFrame fenetre;
	private JSlider base;
	private JPanel p1,p2,p3;
	private JTextField jfield1,jfield2;
	private JLabel label3,label2;
	private JTextArea jarea;
	
	private final static String doc = //aide contenue dans le JTextArea
	"\t\tBrève documentation de cette application...   \n"+
	"\nCe petit programme permet de convertir un nombre en base 10 dans une base comprise entre 2 et 36.\n" +
	"Le \"potentiomètre\" permet de selectionner la base.\n" +
	"La modification d'un champ suivie de la validation par la touche ENTREE met à jour l'autre champ.\n" +
	"Lors d'un changement de la base, la valeur en base 10 est convertie.\n\n"+	
	"Les nombres saisis s'écrivent en utilisant les chiffres de 0 à 9,\n"+
	"puis les lettres de A à Z (miniscules ou majuscules).\n";
	
	private final static String[] chiffres = {"0","1","2","3","4","5","6","7","8","9","A",
	"B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W",
	"X","Y","Z"};
	
	
	//Constructeur
	public Conversions() {
		fenetre = new JFrame("Conversions...");
		Container reser = fenetre.getContentPane();
		label2 = new JLabel("En base 10");
		label3 = new JLabel("En base 2");
//--- haut de la fenetre -------------------------------------------------------------------------------
		String s1 = "Changement de base de numération";
		jarea = new JTextArea(doc);
		jarea.setEditable(false);
		JScrollPane jscroll = new JScrollPane(jarea);
		p1 = new JPanel(new BorderLayout());
		p1.add(jscroll,BorderLayout.NORTH);
		p1.setBorder(BorderFactory.createTitledBorder(s1));
		reser.add(p1,BorderLayout.NORTH);
//--- JSlider ----------------------------------------------------------------------------------------------
		p2 = new JPanel(new GridLayout(0,1));
		String s2 = "Sélection de la base";
		base = new JSlider(2,36,2);
//--- listener du slider -----------------------------------------------------------------------------------
		ChangeListener b = new ChangeListener() {
			public void stateChanged(ChangeEvent e) {
				label3.setText("En base "+base.getValue());
				label3.setHorizontalAlignment(SwingConstants.CENTER);
				String res = "";
				if (jfield1.getText() == null || jfield1.getText().length() == 0){
				    jfield1.setText(JOptionPane.showInputDialog(fenetre,"Entrez un nombre en base 10","Champ \"Base 10\" vide",JOptionPane.QUESTION_MESSAGE));}//if
				String s = jfield1.getText();
				boolean erreur = false;
				for (int i =0;((i<s.length()) && (!erreur));i++) {
					if (!('0'<=s.charAt(i) && s.charAt(i)<='9')) {
						Toolkit.getDefaultToolkit().beep();
						JOptionPane.showMessageDialog(fenetre,"En base 10, on n'utilise uniquement les chiffres entre 0 et 9","Chiffre non autorisé",JOptionPane.ERROR_MESSAGE);
						erreur =  true;
						}//if
				}//for
				if (!erreur) {
				int b = Integer.parseInt(jfield1.getText());
				int n = base.getValue();
				while (b != 0 ) {
				    res = chiffres[b%n]+res;
				    b = b/n;
				}//while
				}//if
				jfield2.setText(res);
			}
		};
		base.addChangeListener(b);
		base.setMajorTickSpacing(2);
		base.setPaintTicks(true);
		base.setPaintLabels(true);
		p2.add(base);
		p2.setBorder(BorderFactory.createTitledBorder(s2));
		reser.add(p2,BorderLayout.CENTER);
//--- les champs de saisie --------------------------------------------------------------------------------------------
		p3 = new JPanel(new GridLayout(0,2));
		jfield1 = new JTextField("");
		jfield2 = new JTextField("");
		jfield1.setHorizontalAlignment(SwingConstants.CENTER);
		jfield2.setHorizontalAlignment(SwingConstants.CENTER);
		label2.setHorizontalAlignment(SwingConstants.CENTER);
		label3.setHorizontalAlignment(SwingConstants.CENTER);
//--- mise a l'écoute des champs ----------------------------------------------------------------------------------------

//--- champ base 10 -----------------------------------------------------------------------------------------------------
		ActionListener b10 = new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String s = jfield1.getText();
				boolean erreur = false;
				for (int i =0;i<s.length() && !erreur;i++) {
					if (!('0'<=s.charAt(i) && s.charAt(i)<='9')) {
						Toolkit.getDefaultToolkit().beep();
						JOptionPane.showMessageDialog(fenetre,"En base 10, on n'utilise uniquement les chiffres entre 0 et 9","Chiffre non autorisé",JOptionPane.ERROR_MESSAGE);
						erreur =  true;
						}//if
				}//for
				if (!erreur) {
					String res = "";
					int b = Integer.parseInt(jfield1.getText());
					int n = base.getValue();
				   	while (b != 0 ) {
						res = chiffres[b%n]+res;
						b = b/n;
					}//while
					jfield2.setText(res);
					}//if
				}//actionPerformed
			};//class anonyme
		jfield1.addActionListener(b10);

//--- champ de la base n -------------------------------------------------------------------------------------------------
		ActionListener bn = new ActionListener() {
			public void actionPerformed(ActionEvent e) {
			    try{
			    jfield1.setText(""+Integer.parseInt(jfield2.getText(),base.getValue()));
			    }catch (NumberFormatException nfe) {
				JOptionPane.showMessageDialog(fenetre,"En base "+base.getValue()+", on utilise les chiffres entre 0 et "+chiffres[base.getValue()-1],"Chiffre non autorisé",JOptionPane.ERROR_MESSAGE);
			    }//catch
				}//actionPerformed
				};//class anonyme
		jfield2.addActionListener(bn);		

//--------------------------------------------------------------------------------------------------------------------		
		p3.add(label2);
		p3.add(jfield1);
		p3.add(label3);
		p3.add(jfield2);
		reser.add(p3,BorderLayout.SOUTH);
		
	}//Conversions()
	
	//affichage
	public void afficher() {
	fenetre.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	fenetre.setSize(650,350);
	fenetre.setResizable(false);
	fenetre.setVisible(true);
	}//afficher
	
	//main
	public static void main (String [] args) {
		Conversions convertisseur = new Conversions();
		convertisseur.afficher();
		}//main
}//class Conversions